1. Field of the Invention
The present invention relates generally to plug connectors for differential transmission, and more particularly to a right angle-type plug connector for differential transmission having L-shaped mounting terminals so as to be mounted on a printed circuit board with the connection part of the plug connector being parallel to the printed circuit board.
2. Description of the Related Art
Differential transmission has been employed in many cases as a method of transmitting data between personal computers and peripheral devices. Differential transmission uses a pair of lines for each data element, and simultaneously transmits a “+” signal to be transmitted and a “−” signal equal in magnitude and opposite in direction to the “+” signal so that the difference in level between the “+” and “−” signals is recognized as information. Differential transmission has the advantage of being less susceptible to noise compared with a normal transmission method.
In order for differential transmission to work properly, the paired lines, one for transmitting the “+” signal and the other for the “−” signal, should be parallel and equal in length. Further, ground potential should be provided between pairs of adjacent lines so that a shield is provided therebetween.
FIG. 1 is a diagram showing a conventional plug connector 10 for differential transmission. In FIG. 1, X1-X2 and Z1-Z2 indicate the directions of width and the directions of height, respectively, of the plug connector 10. Further, Y2 indicates the direction in which the plug connector 10 is inserted to be connected (the insertion and connection direction of the plug connector 10) and Y1 indicates the opposite direction. The plug connector 10 includes a block body 20, which is an electrically insulating molded component of a synthetic resin. Pairs of first and second signal contact members 30-1 and 30-2 and plate-like ground contact members 31 are incorporated into the block body 20 so as to be arranged alternately at predetermined pitches P1 in the X1-X2 directions or along the X-axis.
Each ground contact member 31 includes a mounting terminal part 31a shaped like a fork. A mounting terminal part 30-1a of the signal contact member 30-1 and a mounting terminal part 30-2a of the signal contact member 30-2 extend linearly in the Y1 direction and oppose each other in the Z1-Z2 directions or along the Z-axis.
The mounting terminal parts 31a and the mounting terminal parts 30-1a and 30-2a are soldered to pads on a printed board 40 while holding an edge part of the printed board 40 so that the plug connector 10 is mounted thereon.
Japanese Laid-Open Patent Application No. 2003-059593 discloses such a plug connector.
In recent years, differential transmission plug connectors have been used in a wide variety of modes. For instance, it has been required to mount a differential transmission plug connector on a printed circuit board with the insertion and connection direction of the plug connector being parallel to the surface of the printed circuit board. To this end, the plug connector should be of a right angle type with the mounting terminal parts of paired signal contact members being L-shaped, as parallel to each other as possible, and equal in length.